US2911343A - System for measuring nuclear power - Google Patents

System for measuring nuclear power Download PDF

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Publication number
US2911343A
US2911343A US508613A US50861355A US2911343A US 2911343 A US2911343 A US 2911343A US 508613 A US508613 A US 508613A US 50861355 A US50861355 A US 50861355A US 2911343 A US2911343 A US 2911343A
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United States
Prior art keywords
reactor
screen
measuring
power
output
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Expired - Lifetime
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US508613A
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English (en)
Inventor
Braffort Paul Louis
Weill Jacky
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Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C17/00—Monitoring; Testing ; Maintaining
    • G21C17/10—Structural combination of fuel element, control rod, reactor core, or moderator structure with sensitive instruments, e.g. for measuring radioactivity, strain
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C17/00—Monitoring; Testing ; Maintaining
    • G21C17/10—Structural combination of fuel element, control rod, reactor core, or moderator structure with sensitive instruments, e.g. for measuring radioactivity, strain
    • G21C17/108—Measuring reactor flux
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Definitions

  • the present invention relates to a system for measuring nuclear power, such as a device responsive to the power output of an atomic reactor and adapted to make a record of such output, give a visual indication thereof and/or utilize it for control purposes.
  • Another obstacle to the realization of a measuring system adapted to respond to low-power outputs lies in the substantial amount of background gamma radiation which is present after an extended period of operation of the reactor and which tends to falsify the result even if corrective devices known per se, such as a so-called compensated ionization chamber, are used for the measurement.
  • the present invention has for its object the provision of a measuring system, as hereinabove defined, which avoids the difiiculties referred to and which enables accurate determination of the neutron yield of a reactor under the circumstances described.
  • a feature of this invention resides in the provision of a suitable measuring device, such as conventional cloud chamber or ionization chamber, preferably of the aforementioned compensated type, positioned behind a fixed screen of a material having a relatively high massive absorption coefiicient for gamma rays but a relatively low effective cross section so far as the absorption of neutrons is concerned.
  • the invention provides a second, movable screen having a relatively high effective cross section for the absorption of neutrons, the latter screen being interposed between the measuring device and the reactor proper in the latters high-power stage of operation and being removed in the low-power stage, thus when the reactor is idle.
  • the measuring device with two output means, such as a pair of different meter scales, for high-power and low-power output indication, respectively.
  • the fixed screen should advantageously consist of a material having an atomic weight above 200, such as bismuth, lead, etc. Bismuth is preferred in this class of materials since, in its natural state, it has the least eifective cross section for the absorption of neutrons.
  • the reactor 1 which may be, for example, of the graphite-moderated type, is suitably enclosed in a protective sheath or envelope comprising an inner jacket 2 of iron and an outer shield 3 of concrete.
  • the measuring device associated with the reactor proper comprises an ionization chamber 4 embedded in a recess 6 of a photon-absorbing fixed screen 5, e.g. of bismuth, separating the chamber 4 from the reactor core. It will be noted that the iron jacket 2 is omitted at the screen 5 so as to expose the latter directly to reactors radiation.
  • the output means of the measuring device have been shown, schematically and by way of example, as comprising a first meter 11 for low-power output and a second meter 12 for high-power output, the two meters being selectively connectable to the ionization chamber 4 by means of a switch 10.
  • a neutron-absorbing screen 8 guided by a rail 7 for movement between a retracted position (full lines) and an operative position (dotdash lines), is displaceable by suitable remote-control means indicated schematically at 9.
  • suitable remote-control means indicated schematically at 9.
  • a link 13 whereby the movable screen 8, which may be of boron, is synchronized with the switch 10 so as to activate the low-power meter 11 in its retracted position and the high-power meter 12 in its operated position.
  • Meters 11 and 12 are, of course, properly calibrated to take into account the absence or the presence, respectively, of screen 8 in the neutron path from the reactor to the measuring chamber 4.
  • screen 5 is to minimize or even to eliminate the effect of gamma rays upon the output of chamber 4, especially in the idle or low-power condition of the reactor.
  • the dimensions of this screen may be determined on the basis of the following considerations:
  • the material of screen 5 e.g. bismuth
  • the material of screen 5 has a known absorption coeflicient for gamma rays on the one hand and for neutrons on the other.
  • the total absorption rate for either type of radiation is a function of the efiective depth d of the screen in the region of the ionization chamber.
  • the latter has a predetermined photon/neutron sensitivity ratio (Which may be of the order of li n in the case of an ordinary boron-charged chamber and of the order of A in the case of a compensated chamber) which, together with the known flux ratio of gamma radiation and neutrons impinging from the reactor upon the bismuth screen, determines the minimum permissible depth d of the screen.
  • This depth may have a value of the order of 20 to 50 cm. or more.
  • a reactor in combination, a reactor, a shield surrounding said reactor, an ionization chamber measuring means mounted in fixed position within said shield sensitive to radiations emanating from said reactor, a screen fixed within said shield so as to be interposed between said reactor and said measuring means, said fixed screen being made of a material capable of absorbing gamma rays While being of relatively high permeability to neutrons, whereby gamma rays from said reactor are permanently prevented from acting upon said measuring means, another screen located within the space limited by the external surface of said shield, said second mentioned screen being mounted movable with respect to said shield so as to be able to occupy either a position where it lies across the path of said radiations between said reactor and said ionization chamber measuring means or a position outside of said path, said second mentioned screen being made of a material of relatively low permeability to neutrons, means operative from outside of said shield for shifting said second mentioned screen from one of its positions to the other, whereby it is possible either to let the neutron flux from said reactor

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Measurement Of Radiation (AREA)
US508613A 1954-05-17 1955-05-16 System for measuring nuclear power Expired - Lifetime US2911343A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR1016854X 1954-05-17

Publications (1)

Publication Number Publication Date
US2911343A true US2911343A (en) 1959-11-03

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Family Applications (1)

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US508613A Expired - Lifetime US2911343A (en) 1954-05-17 1955-05-16 System for measuring nuclear power

Country Status (5)

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US (1) US2911343A (enrdf_load_stackoverflow)
DE (1) DE1016854B (enrdf_load_stackoverflow)
FR (1) FR1104885A (enrdf_load_stackoverflow)
GB (1) GB780219A (enrdf_load_stackoverflow)
NL (2) NL91797C (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3003941A (en) * 1958-11-12 1961-10-10 Allis Chalmers Mfg Co Nuclear reactor
US3089958A (en) * 1957-11-27 1963-05-14 Siemens Ag Jacketed neutron-flux measuring gage for nuclear reactors
US3393126A (en) * 1966-11-07 1968-07-16 Atomic Energy Authority Uk Testing for fuel element sheathing failures in nuclear reactors
US3393125A (en) * 1965-11-12 1968-07-16 Atomic Energy Authority Uk Testing for fuel element sheathing failures in nuclear reactors
US3717765A (en) * 1970-04-04 1973-02-20 Siemens Ag Device for non-destructive consumption testing of reactor fuel elements
US4261794A (en) * 1978-02-09 1981-04-14 Bunker Ramo Corporation Radiation shielding for electric penetration assemblies
DE102012006057A1 (de) * 2012-03-27 2013-10-02 Kaiser Gmbh & Co Kg Installationsdose für elektrotechnische Anwendungen

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1055145B (de) * 1957-11-22 1959-04-16 Siemens Ag Ummantelung fuer Neutronenfluss-Messsonden
US3050624A (en) * 1958-03-14 1962-08-21 Siemens Ag Neutron-flux gage for nuclear reactors

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2522522A (en) * 1941-05-03 1950-09-19 Schlumberger Well Surv Corp Shielding method and apparatus for radioactive borehole logging
US2708656A (en) * 1944-12-19 1955-05-17 Fermi Enrico Neutronic reactor
US2719823A (en) * 1945-08-17 1955-10-04 Walter H Zinn Neutronic reactor radiation indicator
US2763788A (en) * 1950-12-22 1956-09-18 Texas Co Induced and scattered gamma ray well logging
US2785314A (en) * 1951-09-28 1957-03-12 Texas Co Radioactivity earth exploration

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2522522A (en) * 1941-05-03 1950-09-19 Schlumberger Well Surv Corp Shielding method and apparatus for radioactive borehole logging
US2708656A (en) * 1944-12-19 1955-05-17 Fermi Enrico Neutronic reactor
US2719823A (en) * 1945-08-17 1955-10-04 Walter H Zinn Neutronic reactor radiation indicator
US2763788A (en) * 1950-12-22 1956-09-18 Texas Co Induced and scattered gamma ray well logging
US2785314A (en) * 1951-09-28 1957-03-12 Texas Co Radioactivity earth exploration

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3089958A (en) * 1957-11-27 1963-05-14 Siemens Ag Jacketed neutron-flux measuring gage for nuclear reactors
US3003941A (en) * 1958-11-12 1961-10-10 Allis Chalmers Mfg Co Nuclear reactor
US3393125A (en) * 1965-11-12 1968-07-16 Atomic Energy Authority Uk Testing for fuel element sheathing failures in nuclear reactors
US3393126A (en) * 1966-11-07 1968-07-16 Atomic Energy Authority Uk Testing for fuel element sheathing failures in nuclear reactors
US3717765A (en) * 1970-04-04 1973-02-20 Siemens Ag Device for non-destructive consumption testing of reactor fuel elements
US4261794A (en) * 1978-02-09 1981-04-14 Bunker Ramo Corporation Radiation shielding for electric penetration assemblies
DE102012006057A1 (de) * 2012-03-27 2013-10-02 Kaiser Gmbh & Co Kg Installationsdose für elektrotechnische Anwendungen
DE102012006057B4 (de) * 2012-03-27 2016-06-02 Kaiser Gmbh & Co Kg Installationsdose für elektrotechnische Anwendungen

Also Published As

Publication number Publication date
NL91797C (enrdf_load_stackoverflow)
GB780219A (en) 1957-07-31
NL197303A (enrdf_load_stackoverflow)
DE1016854B (de) 1957-10-03
FR1104885A (fr) 1955-11-24

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